DE4237438A1 - Aqueous dispersion or solution crosslinking with divinyl ether - Google Patents

Description

The invention relates to an aqueous dispersion or solution of a radical polymer which consists of 0.01 to 10 wt .-% of carboxylic acid groups -CO ₂ H or sulfonic acid groups -SO ₃ H, containing as a crosslinking agent a compound with at least two vinyl ether groups.

For copolymers that are used as adhesives find, it is often networkable Copolymers. Through networking, cohesion d. H. the internal strength of the adhesives while, however the adhesion to the substrate surfaces to be glued in general decreases.

The copolymers are generally used for crosslinking Crosslinking agent added with functional groups reacted in the copolymer.

Possible crosslinking agents are e.g. B. polyisocyanates, which react with hydroxyl or amino groups.

From DE-A-35 21 618 there are corresponding aqueous adhesives preparations known in which dispersed in water Polyisocyanates aqueous dispersions radical polymeri based copolymers added as crosslinking agents become. Similar adhesive preparations are also in the US-A 4 396 738 and DE-A-31 12 117.

However, the disadvantage of these aqueous preparations is that lack of storage stability. The polyisocyanate is therefore only allowed shortly before its use as a crosslinking aid in Dispersed water and mixed with the copolymer become.

Increased storage stability can be achieved by implementing the Iso cyanate groups with blocking agents, e.g. B. Oximen, Capro lactam, phenols, maleic acid dialkyl esters can be achieved.  

Hydrolyze the so-called blocked polyisocyanates obtained in aqueous dispersion only to a minor extent.

The subject of DE-A-38 07 555 is one with oximes blocked diisocyanate, which is dispersed in water and as an additive for polymers dispersed in water is suitable.

Crosslinking reactions, however, only occur after the Blocking agent at temperatures above approx. 130 ° C.

Previously known aqueous adhesive preparations with polyiso Cyanates as crosslinking aids are therefore either not stable in storage and can therefore only be used as a 2-component system Find or use only at high Temperatures.

Storage stable, at room temperature after removing the solution by means of crosslinking aqueous dispersions are from the EP-A-3516 known. These dispersions contain poly hydrazides which are copolymerized with in the copolymer React monomers with carbonyl groups.

Basically there is a need for more, at room temperature crosslinking dispersions to find alternatives to poly to be able to provide hydrazide crosslinking. Of furthermore, these dispersions are said to have good application properties Properties, e.g. B. when used as an adhesive good adhesion (adhesion), especially good wet grip on a wide variety of substrates, and good cohesion exhibit.

Divinyl ethers as crosslinking agents are from the SU-A-1 235 879 and FR-A-2 558 845 are known. After SU-A-1 235 879 divinyl ethers become liquid, carboxylated rubber added and the mixture at 80 ° C. vulcanized. According to FR-A-2 558 845, divinyl ethers as a crosslinking agent at temperatures between 150 and 200 ° C with carboxyl-containing polyolefins ver mixes and suitable substrates at temperatures between 200 and 250 ° C coated with the mixture obtained.

The object of the present invention was storage-stable, aqueous dispersions of crosslinkable copolymers, which contain a crosslinking agent and at room temperature can be networked.

The object of the present invention was also aqueous Adhesives, especially pressure sensitive adhesives, which are good Have cohesion and adhesion.

Accordingly, the dispersion or solution defined above as well as their use as an adhesive.

The crosslinking reaction of carboxylic or sulfonic acid group-containing polymers with vinyl ethers probably according to the following reaction scheme:

The carboxylic acid or sulfonic acid group adds up to the double bond of the vinyl ether.

The aqueous dispersions or solutions according to the invention contain a radical polymer, which to 0.01 to 10 wt .-%, preferably 0.05 to 3 wt .-% and especially before adds 0.1 to 2 wt .-% of carboxylic or sulfonic acid groups exists.

The carboxylic acid or sulfonic acid groups can e.g. B. by polymer-analogous reactions or radical copolymers tion of suitable carboxylic acid or sulfonic acid groups containing compounds (hereinafter referred to as compounds a) referred to) be built into the radical polymer.  

Are suitable for. B. Compounds a) which, in addition to at least one sulfonic acid or carboxylic acid group, at least one further functional group z. B. contain further carboxylic acid groups, carboxylic anhydride groups, primary or secondary amino groups, hydroxyl groups or epoxy groups as an additional functional group (hereinafter referred to as functional compound a ₁ )).

The functional connection can be done with a corresponding function nalized polymers are implemented, for. B. responds Connection with a carboxylic or carboxylic anhydride group easily as an additional functional group primary or secondary amino groups in the polymer chain. A compound with an epoxy group also reacts as additional functional group easily with hydroxyl groups or primary or secondary amino groups in the polymer main chain.

For the incorporation of carboxylic acid or sulfonic acid groups into the radical polymer, the copolymerization of copolymerizable ethylenically unsaturated monomers which contain at least one carboxylic acid or sulfonic acid group (hereinafter referred to as monomers a ₂ ) is preferred.

Examples of monomers a ₂ ) include acrylic acid, methacrylic acid, maleic acid, fumaric acid or vinyl sulfonic acid.

The radical polymer can, in addition to the compounds a) so-called radically polymerizable main monomers b) and optionally further free-radically polymerizable Contain secondary monomers c) which do not contain carboxylic acid or Have sulfonic acid groups.

Monomers b) are esters of acrylic or methacrylic acid of 1 to 20 C-containing alkyl alcohols in Be dress. Alcohols such as methanol, ethanol, n- or i-propanol, n-, s- and t-butanol, n-pentanol, iso amyl alcohol, n-hexanol, octanol, 2-ethyl hexanol, lauryl and Stearyl alcohol.  

Good results are obtained with (meth) -acrylic acid alkyl esters with a C ₁ -C ₁₀ -alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.

In particular, mixtures of (meth) acrylic acid alkyl are also suitable ester.

Furthermore, vinyl esters of carboxylic acids come with 1 to 20 carbon atoms such as vinyl laurate, stearate, vinyl propionate and Vinyl acetate into consideration.

As vinyl aromatic compounds with up to 20 carbon atoms come vinyltoluene, α- and p-styrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene in Consideration. Examples of ethylenically unsaturated nitriles are acrylonitrile and methacrylonitrile.

The vinyl halides are substi with chlorine, fluorine or bromine tuiert ethylenisch unsaturated compounds, preferred Vinyl chloride and vinylidene chloride.

As non-aromatic hydrocarbons with 2 to 8 carbon atoms and at least two conjugated olefinic Double bonds are butadiene, isoprene and chloroprene called.

The monomers b) can in particular also be in a mixture be placed, especially to desired glass transition adjust temperatures of the copolymer.

As another, d. H. copolymerizable from b) Monomers c) be z. B. esters of acrylic and methacrylic acid of alcohols with 1 to 20 carbon atoms, which in addition to the acid Substance atom in the alcohol group at least one more Contain heteroatom and / or an aliphatic or contain aromatic ring called.

Consider z. B. 2-ethoxyethyl acrylate, 2-butoxy ethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, Diethylaminoethyl (meth) acrylate, (meth) acrylic acid aryl, alkaryl or cycloalkyl esters, such as cyclohexyl (meth) acrylate, phenylethyl (meth) acrylate, phenylpropyl (meth) -  acrylate or acrylic acid esters of heterocyclic alcohols such as furfuryl (meth) acrylate.

In addition, (meth) acrylamide and its derivatives substituted on nitrogen with C ₁ -C ₄ -alkyl may be mentioned as possible monomers c).

Also of particular importance are hydroxy-functional monomers c), e.g. B. (meth) acrylic acid-C ₁ -C ₁₅ alkyl esters which are substituted by one or two hydroxyl groups. Of particular importance as hydroxy-functional comonomers are (meth) acrylic acid-C ₁ -C ₈ -hydroxyalkyl esters, such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl (meth) acrylate.

Maleic anhydride or may also be mentioned Glycidyl (meth) acrylate.

The weight fraction of the monomers b) in the polymer can be 30 to 99.99, preferably 60 to 99.9 and particularly preferably 80 up to 99.5% by weight; that of the monomers c) can be 0 to 60, preferably 0 to 30, particularly preferably 0 to 10% by weight be.

The weight fraction of the compounds a) is then chosen so that the weight percentages of the monomers and given if the functional connections add up to 100% and the polymer has the carbon content described above has acid or sulfonic acid groups.

The glass transition temperature of the polymer is in all generally between -50 and + 140 ° C, preferably between -30 and + 100 ° C.

The glass transition temperature of the polymer can be reduced usual methods like differential thermal analysis or Differential scanning calorimetry (see ASTM 3418/82, so-called "midpoint temperature").

When used as an adhesive, in particular as a pressure sensitive adhesive, the glass transition temperature is preferably between -30 and + 10 ° C. Suitable monomers b) in this case are in particular C ₁ -C ₂₀ -, preferably C ₁ -C ₈ -alkyl (meth) acrylates, optionally in a mixture with vinyl aromatics, preferably styrene.

The polymer can be prepared by conventional polymerization methods, such as bulk, emulsion, suspension or solution polymers be produced.

The polymer is preferably polymerized by emulsion tion produced, the polymer as an aqueous dispersion sion is obtained.

The monomers can be used in emulsion polymerization such as usual in the presence of a water-soluble initiator and polymerized an emulsifier at preferably 30 to 95 ° C. become.

Suitable initiators are e.g. B. sodium, potassium and Ammonium persulfate, tert-butyl hydroperoxides, water-soluble Azo compounds or redox initiators.

As emulsifiers z. B. Long chain alkali salts Fatty acids, alkyl sulfates, alkyl sulfonates, alkylated aryl sulfonates or alkylated biphenyl ether sulfonates.

Furthermore, reaction products come from as emulsifiers Alkylene oxides, in particular ethylene or propylene oxide Fatty alcohols, acids or phenol, or alkylphenols in Consideration.

To adjust the molecular weight in the poly merization controller can be used. Are suitable for. B. -SH containing compounds such as mercaptoethanol, mercapto propanol, thiophenol, thioglycerin, thioglycolic acid ethyl esters, methyl thioglycolate and tert-dodecyl mercaptan.

The aqueous dispersion or solution according to the invention contains as a crosslinking agent, a compound with at least two Vinyl ether groups

preferably with two or three, very particularly preferred with two vinyl ether groups.

These are preferably vinyl ethers of the formula

wherein A is an n-valent linear or branched hydrocarbon chain of 2 to 40 carbon atoms, which may be interrupted by 1 to 19 non-adjacent oxygen, nitrogen or sulfur atoms or by one or two C ₅ -C ₁₀ cycloaliphatic or C ₅ - C ₁₂ aromatic ring systems may be substituted or interrupted, or represent an n-valent C ₅ -C ₁₀ cycloaliphatic or C ₅ -C ₁₂ aromatic ring system and n may be an integer from 2 to 6 and R ¹ , R ² and R ³ independently represent a hydrogen atom or a C ₁ -C ₄ alkyl group.

A particularly preferably represents a linear or branched Hydrocarbon chain of 2 to 25 carbon atoms, which may not be adjacent by 1 to 12 Oxygen atoms is interrupted or by a cyclo hexyl or cyclohexylene ring substituted or interrupted is.

n is preferably 2, 3 or 4.

N = 2 is particularly preferred.

R ¹ , R ² and R ³ preferably represent a hydrogen atom.

Examples of vinyl ethers which may be mentioned are butanediol divinyl ether, hexanediol divinyl ether, pentaerythritol tetra vinyl ether, trimethylol propane trivinyl ether, ethylene glycol di  vinyl ether, tetramethylene glycol divinyl ether or 1,4-cyclo hexanedimethanol divinyl ether.

Divinyl ethers of polyalkyls are also particularly suitable noxides, e.g. B. polyethylene oxides or polytetrahydrofurans.

Polyacetals with terminal viny are also suitable lether groups, such as easily z. B. by adding diols on divinyl ethers.

Vinyl ethers other than Formula I can also be used. Consider z. B. vinyl ethers of polyalkylene oxides or polyacetals with more than 40 carbon atoms in the hydrocarbon chain and an average molecular weight M _n of up to 10,000 preferably up to 2,000 (determined by gel permeation chromatography, tetrahydrofuran as eluent and polystyrene standard). Vinyl ethers of polyester diols or radical polymers containing hydroxyl groups may also be mentioned.

The vinyl ethers are known as such. You can easily are produced by vinylation of the corresponding Di- or polyalcohols with acetylene.

In general, the vinyl ether compound content is in the dispersions or solutions according to the invention at 0.1 to 10 wt .-%, preferably 0.1 to 5 wt .-%, based on the radical polymer.

There may also be a significant excess or deficit in the Vinyl ether groups, based on the carboxylic acid or sulfone acid groups, are used.

The dispersions or solutions according to the invention contain the vinyl ether compounds preferably in such amounts, that the vinyl ether groups to the carboxylic acid or sulfone acid groups are approximately equimolar.

The solids content of the dispersion according to the invention or Solution is preferably between 20 and 90 wt .-%, in particular the other between 30 and 70 wt .-%.  

The dispersion or solution according to the invention, in particular the dispersion, is suitable as a coating agent for different substrates with plastic, wood or Metal surfaces or z. B. for textiles, non-woven fabrics, Leather or paper. It is also suitable for applications in construction chemistry, e.g. B. as adhesives, sealants, Bin demittel or the like. With the coatings it can be e.g. B. to paint, protective coatings or adhesive coating act against.

The dispersion or solution according to the invention may vary Usage contain customary auxiliaries and additives. These include, for example, fillers such as quartz flour, Quartz sand, finely divided silica, heavy spar, calcium carbonate, chalk, dolomite or talc, often together with suitable wetting agents such. B. polyphosphates such as sodium hexamethaphosphate, naphthalenesulfonic acid, ammonium or Sodium polyacrylic acid salts are used, the Wetting agents generally from 0.2 to 0.6 wt .-%, based on the filler.

If desired, fungicides for preservation are used in all in general in amounts of 0.02 to 1 wt .-%, based on the entire dispersions or solution used. Suitable Fungicides are, for example, phenol or cresol derivatives or organotin compounds.

The dispersion according to the invention is particularly suitable as Sealant or adhesive, especially e.g. B. as a pressure sensitive adhesive fabrics. The dispersions can be used as an adhesive alongside mentioned additives still special, in the adhesive technology aids and additives included. These include, for example, thickeners, plasticizers or also tackifying resins such as. B. natural resins or modified resins such as rosin esters or synthetic Resins like phthalate resins.

The dispersion or solution according to the invention is stable on storage. The crosslinking reaction occurs at room temperature Removing the liquid phase, d. H. the volatilization of the Water.  

By increasing the temperature z. B. to 30 to 100 ° C Ver volatility of the water can be accelerated.

When used as an adhesive, e.g. B. result in pressure sensitive adhesive bonds with high internal strength (cohesion) and at the same time good adhesion (adhesion) to the substrates.

When used as a coating agent for leather especially the fastness to wet rubbing and good elasticity of the highlight coated leather.

Examples I Preparation of polymer dispersions D1 to D6

150 g of water were placed in a reaction vessel with a stirrer and two feed vessels. The feed vessels contained the following mixtures:
Inlet 1:
550 g monomer mixture according to Table 1
8.56 g of a 45% aqueous solution of C12-alkyldiphenyl ether sulfonate (Dowfax® 2A1 from Dow Chemicals) 11.0 g of a 15% aqueous solution of sodium lauryl sulfate
0.66 g of tert-dodecyl mercaptan
190 g water.
Inlet 2:
100 g water
1.65 g sodium peroxodisulfate.

The initial charge was heated to 85 ° C. and 1% by weight of the feed fes 1 and 20% by weight of feed 2 are added with stirring. After polymerizing for 15 minutes, feed 1 was added in 150 minutes closed, with the addition of Feed 1 only 40 g were added continuously. The rest from feed 1 was then continuous in 135 min admitted. The feed 2 was fed continuously in 3 h  give. The polymerization was continued at 85 ° C. for about 2 hours and then cooled. Then was with a 25% aqueous ammonia solution adjusted to pH 7.0.

The polymer dispersions D1 to D6 were correspondingly produced.

Table 1

II Addition of crosslinkers

200 g of the dispersions were at room temperature with stirring with the amounts listed in Table 2 Crosslinkers added and approx. 1 h at R.T. touched.

III Application test

To test the application properties, the dispersions or their mixtures were knife-coated with an application weight of approximately 20 g / m ² onto polyester film (Hostaphan RN36, Hoechst) and the coated films were dried for 3 minutes at 90 ° C. in a circulating air drying cabinet. The coated foils were then cut into 2 cm wide test strips.

To determine the shear strength (measure of cohesion) the adhesive strips in 2.5 cm length on a chromed V2A test sheet glued, with a 2 kg roll once rolled on, stored for 24 h and then hanging at 23 ° C loaded with a 2 kg weight. The measure of the sharpness Steadiness was the time until the weight dropped; it the average of 3 measurements was calculated.

When determining the peel strength (measure of adhesion) was an adhesive strip on a chromed V2A test sheet glued and with a 1 kg roll 1 rolled up and stored for 24 hours. He was then with one End in the upper jaws of a tensile strain tester clamped. The adhesive tape was under at 300 mm / min subtracted from the test surface (V2A steel) at a 90 ° angle and measured the effort required. The measure of the peel value was the force in N, which was an average resulted from 3 measurements.

The determination of the loop value (measure of adhesion) was carried out according to Federation Inter nationale des Fabricants Transformateurs d′Adhesifs et Thermocollants sur Papiers et Autres Supports (FINAT).

To determine the loop value, a 17.5 cm long and 2 cm wide test strips by clamping both A loop ends in the jaws of a tractor formed, which then with a chromed steel surface at a speed of 30 cm / min (lowering the Loop on the chromed steel sheet) becomes. After full contact, the loop is immediately subtracted again and the maximum force determined in N determined as a measure of the loop value.

The test numbers were used to assess the networking effect PZ1 and PZ2 used. PZ1 is the product Peel strength and shear strength, PZ2 is the product of the loop value, the shear strength and the peel strength speed.  

Results are also shown in Table 2.
Abbreviations:
BDDVE = butanediol divinyl ether
CHDMDVE = cyclohexanedimethanol divinyl ether
PTHF-DVE = polytetrahydrofuran divinyl ether (molecular weight Mn approx. 400)
ADDH = adipic acid dihydrazide.

Claims (6)

1. Aqueous dispersion or solution of a radical polymer, which consists of 0.01 to 10 wt .-% of carboxylic acid groups -CO ₂ H or sulfonic acid groups -SO ₃ H, containing as a crosslinking agent a compound with at least two vinyl ether groups. 2. Aqueous dispersion according to claim 1, containing at least one vinyl ether of the formula as crosslinking agent wherein A is an n-valent linear or branched aliphatic hydrocarbon chain of 2 to 40 carbon atoms, which are optionally interrupted by 1 to 19 non-adjacent oxygen, nitrogen or sulfur atoms or by one or two C ₅ -C ₁₀ cyclo aliphatic or C ₅ -C ₁₂ aromatic ring systems can be substituted or interrupted, or stands for a n-valent C ₅ -C ₁₀ cycloaliphatic or C ₅ -C ₁₂ aromatic ring system, n can be an integer from 2 to 6 and R ¹ , R ² and R ³ independently of one another represent a hydrogen atom or a C ₁ - to C ₄ -alkyl group. 3. Dispersion according to claim 1 or 2, containing a copolymer with a glass transition temperature between -50 and + 140 ° C, wherein the copolymer

• a) at least one compound with at least one carboxylic acid or sulfonic acid group
• b) 30 to 99.99% by weight of at least one C ₁ to C ₂₀ alkyl (meth) acrylate, a vinyl ester of carboxylic acids containing 1 to 20 C atoms, a vinyl aromatic with up to 20 C atoms, one ethylenically unsaturated nitrile with 3 to 6 carbon atoms, a vinyl halide or a non-aromatic hydrocarbon with 4 to 8 carbon atoms and at least 2 conjugated double bonds, and
• c) contains 0 to 60% by weight of at least one further ethylenically unsaturated monomer, the content of compound a) being chosen so that the copolymer contains 0.01 to 10% by weight of carboxylic acid or sulfonic acid groups and itself add the weight percentages of a), b) and c) to 100% by weight.

4. Use of an aqueous dispersion according to one of the Claims 1 to 3 as an adhesive. 5. Use of an aqueous dispersion according to one of the Claims 1 to 3 as a coating agent for leather. 6. Coated substrates available using a dispersion according to any one of claims 1 to 3.